January 26, 2005

Little Benefit From Whole-Body CT Scans

HealthDayNews -- It sounds like a good idea: Regular computed tomography (CT) scans of the entire body, looking for aberrations that might signal early signs of disease.

But a new study suggests these scans -- which cost about $900 apiece -- do little to boost long-term health, and might even undermine patient care.

The study found that whole-body scans added just six days of life expectancy to the average 50-year-old male patient, and that each scan came with a high risk for false-positive findings that might necessitate further, expensive tests.

"A very substantial portion of the total program cost would be related, then, to the work-up of these false positives, of absolutely no benefit to the patient," explained lead researcher Dr. G. Scott Gazelle, a professor of radiology at Harvard Medical School.

One expert radiologist disagreed with Gazelle's conclusions, however.

Dr. Michael Brant-Zawadzki, medical director of radiology at Hoag Memorial Hospital, in Newport Beach, Calif., believes full-body scans are still useful in "capturing people's attention to the concept of screening for highly prevalent disease such as heart disease, lung and colon cancer at earlier stages."

The findings appear in the February issue of Radiology.

Over the past few years, private radiology centers specializing in full-body CT examinations have sprung up across the country. According to Gazelle, consumers can expect to spend an average of $900 each for these scans, which are typically not covered by Medicare or private health plans.

"At the time they were introduced, there was a lot of marketing, of course," Gazelle said. "But there was also concern that there really wasn't any evidence that this was beneficial."

Because a real-life study into the cost and benefits was not feasible, the Harvard team turned instead to a detailed mathematical model to help determine the cost-effectiveness of full-body scans.

The model "looked at eight conditions commonly said to be evaluable by whole-body CT," Gazelle said. "We then ran hypothetical cohorts of half a million people through this model, and calculated [added] life expectancy and costs for that cohort."

The results, according to Gazelle, were less than impressive. In one model -- involving 50-year-old American males screened for a variety of cancers and cardiovascular disease -- CT scans added just six days to overall lifespan, the researchers found.

Gazelle also noted that single-organ CT scans looking for specific diseases typically carry more than a 10 percent rate of false-positive findings -- tissue aberrations that appear suspicious but prove to be benign. Because the full-body scan used in the model was designed to spot eight different conditions, the Harvard team calculated its potential false-positive rate at over 90 percent.

"So, let's say somebody has a false-positive result on a whole-body CT scan," Gazelle said. "They then come in [to their doctor] and need perhaps three follow-up tests for $10,000 worth of additional work-up. Well, the health-care system is going to pay for that, and that drives everyone's costs up."

According to the researchers, the full-body scan's net gain of six days of life per user would cost each patient $2,513, on average. Burdens on the health-care system would be even greater -- Gazelle's team calculated that the amount of full-body screening needed to gain one patient one extra year of life would cost the U.S. health-care system $151,000. That figure exceeds the cost of most health-care interventions currently funded in this country, he said.

Even patients whose scans show no apparent problems may lose in the long run, Gazelle said. "There's reason to believe that people would do this [scan] and then not participate in other health-care interventions that are known to be beneficial," he said.

But Brant-Zawadzki believes full-body scans can still play a key role in the early detection of disease. "The whole concept of screening, for me, is one of raising people's consciousness about the fact that there's now a tool available to detect three of the major killers in our society -- heart disease, lung cancer and colon cancer," he said.

And he remains dubious that any mathematical model can accurately assess the usefulness of a procedure that's only been available to patients for the past few years. "You can't really do a cost-effectiveness analysis on a test that hasn't been truly evaluated," Brant-Zawadzki said. In a mathematical model, researchers by necessity make "major assumptions," he added.

But Gazelle countered that this type of modeling has a long, respected history in scientific research. "Decision models have been used to guide public policy, in cardiovascular disease, cancers and other diseases, for the last 20 or 30 years," he said.

He believes the findings could help dampen public enthusiasm for full-body scans.

"Basically, I think whole-body CT scanning preys on the worried well," Gazelle said. "That's what many of these centers wanted early on. They made people happy that they didn't have anything, they told them they were fine, and collected the money."